Inserting Code Chunks into RMarkdown/Quarto

Introduction

This is a short post to demonstrate a function that can be used to insert code chunks, from a library of chunks, into an active RMarkdown or Quarto document. The concept is simple - read in a chunk of code from a location, in this case GitHub, and use functions from {rstudioapi} to insert it at the current cursor position.

Code and Example

add_code_chunk <- function(snippet = NULL, fences = TRUE) {

  if (!is.null(snippet)) {
    location <- "https://raw.githubusercontent.com/harveyl888/insert-chunks/refs/heads/main/"
    snippet_location <- paste0(file.path(location, snippet), ".qmd")
    s <- readLines(snippet_location) |>
      paste(collapse = "\n")

    if (fences == TRUE) {
      s <- paste("```{r}", s, "```", sep = "\n")
    }

    ## inject at current cursor position
    l <- rstudioapi::getSourceEditorContext()
    rstudioapi::insertText(text = s, id = l$id)

  }
}

The function can be run from the console add_code_chunk("testfile_01", chunk = TRUE) to insert the contents of harveyl888/insert-chunks/testfile_01.qmd at the current cursor position. With fences = TRUE the chunk fences will be included.

The two {rstudioapi} functions take care of placing the content at the cursor. rstudioapi::getSourceEditorContent() grabs details of the current open editor window. It returns a list with the follow members:

• id. A unique ID
• path. The document path
• contents. The document contents
• selection. The currently selected region range

For the purpose of inserting code, we want to capture the id, so that we can refer to the open document.

The second function, rstudioapi::insertText() inserts text into a chosen document. We use the document id returned by rstudioapi::getSourceEditorContent() and place text at the current cursor position.

Here’s an initial document

## Heading

Some initial text

and here it is after scrolling to the end and executing add_code_chunk("testfile_01", chunk = TRUE)

## Heading

Some initial text

```{r}
df <- mtcars |>
  dplyr::filter(cyl == 6)
print(nrow(df))
```